EP0185660B1 - Stabilized aqueous zeolite suspension - Google Patents

Abstract

Stabilized aqueous zeolite A suspensions containing a nonionic surfactant as a stabilizer and an anionic surfactant as a stabilizer auxiliary are improved by using at least one sulfated C10-20 alcohol or substituted alcohol as the stabilizer auxiliary. In a further embodiment, an acid salt may be added to the suspension to adjust the pH to below 12.

Description

The invention relates to a stabilized, aqueous suspension of synthetically produced zeolite of type A, a process for the production of this suspension on an industrial scale and the use of the suspension for the production of low-phosphate and phosphate-free powdered detergents and cleaning agents.

The use of type A synthetic zeolites, in particular NaA zeolite, as a detergent builder and thus as a substitute for sodium tripolyphosphate in detergents and cleaning agents has become increasingly important in recent years. Numerous zeolite-containing detergents with low-phosphate and phosphate-free formulations have already appeared on the market. However, the use of zeolite A as a novel water-insoluble detergent component on an industrial scale has also led to new developments in detergent technology; The processing of the zeolite as a storage-stable, free-flowing suspension with the highest possible zeolite content should be emphasized here. (For the production of zeolite-containing detergents, in particular using stabilized zeolite suspensions, see above Koch, Seifen-Öle-Fette-Wwachs, 106 (1980), pages 321 to 324.)

The stabilization of zeolite suspensions, which are still flowable even after storage and transport, and which can be stirred and pumped through lines, and the use of such suspensions for the production of powdered detergents are known from German Offenlegungsschrift 25 27 388. A number of six different organic and inorganic classes of compounds are proposed as stabilizers; this also includes certain poorly soluble nonionic surfactants. In the German Offenlegungsschrift 27 02 979 certain adducts of amines or glycols with alkylene oxides are recommended as stabilizers for aqueous zeolite suspensions. According to the teaching of German Offenlegunsschrift 26 15 698, the stabilizers of DE-OS-25 27 388 together with a stabilizing aid from the group of non-surfactant organic and inorganic water-soluble salts with molecular weights below 1,000, z. B. sodium sulfate, sodium citrate, sodium tripolyphosphate, sodium carbonate, etc. used; this gives greater flexibility in adapting the viscosity of the suspensions to the storage and processing conditions.

With the increasing interest of the detergent industry in the use of zeolite as a detergent builder instead of triphosphate, numerous further proposals have been made for the preparation and composition of stabilized, aqueous zeolite suspensions. For example, 28 54 484, 30 16 433 and 30 26 511 polymer compounds with a very high molecular weight of the type of acrylamide / acrylic acid copolymers or of ethyl acrylate / methacrylic acid copolymers are specified as stabilizers for aqueous zeolite suspensions in the German patent applications. Stabilizers of the type of phosphoric acid mono- or diesters of fatty alcohol ethoxylates have become known from German Offenlegungsschrift 30 30 955. The use of certain organic and inorganic water-soluble salts as stabilizers, which are used alone or in conjunction with nonionic surfactants, has also become known from a number of publications. For example, German Offenlegungsschrift 30 21 295 recommends the use of nitrilotriacetate sodium salt; on the other hand, water glass solutions, gel-like aluminum oxides or silicon oxides, soaps of chain length C ₅ -C ₂₂ , or sodium salts of the type of washing alkalis, including sodium hydroxide, are described in Japanese laid-open patent applications 54 064 504, 55 127 499, 57 034 017, 57 061 615 and 57 067 697 proposed.

The requirements for the properties of the zeolite suspensions depend to a certain extent on the type of washing and cleaning agents for which they are to be used; However, it has been found that, in order to be usable on an industrial scale, the zeolite suspensions should have the following individual properties: stability in the widest possible temperature range, which ranges from room temperature or below to at least 70 ° C .; a sediment, if it arises after prolonged storage, must be able to be stirred up again using technical stirrers; the viscosity should remain low even in the lower temperature range, i. H. Ensure stirrability and pumpability; when the stabilizers are incorporated, there should be no dilution of the suspension and no impairment of the pH; Finally, it is expected that the suspension stabilizers in the final detergent product do not interfere, but rather are well compatible with all other detergent components and preferably themselves contribute to the washing and cleaning effect. Of the numerous suspension stabilizers proposed so far, the poorly soluble nonionic surfactants, optionally with the addition of an inorganic electrolyte, have so far proven their worth in practice, since these stabilizers and the zeolite suspensions stabilized therewith have the required properties to a considerable extent. However, in order to further expand the economic preferred position of the aqueous zeolite suspensions over the zeolite powders in the production of detergents and cleaning agents, it was desirable to improve the rheological properties of the zeolite suspensions, and thus greater flexibility in use, for example through longer storage stability To ensure portability and universal applicability for the different technical detergent manufacturing processes.

• a) Schwefelsäuremonoester primärer, geradkettiger oder verzweigter Alkohole der Kettenlänge C₁₀-C₂₀, vorzugsweise C₁₂-C₁₈-, oder Schwefelsäuremonoester von sekundären, geradkettigen oder verzweigten C_1Q-C_2o-Alkoholen in Form der wasserlöslichen Salze oder
• b) sulfatierte Umsetzungsprodukte der primären und sekundären Alkohole gemäß a) mit Ethylenoxid, oder sulfatierte Fettsäurealkanolamide oder sulfatierte Fettsäuremonoglyceride in Form der wasserlöslichen Salze, oder aus Mischungen von a) und b) zusammengesetzt ist.

It has now surprisingly been found that the stabilized aqueous zeolite suspension, which consists of industrially produced A-type zeolite, water and a stabilizer system with water-insoluble nonionic surfactant as a suspension stabilizer and an additional stabilizing aid, can be significantly improved in their properties if the stabilization aid from an anionic sulfate surfactant from the group

• a) sulfuric acid monoesters of primary, straight-chain or branched alcohols of chain length C ₁₀ -C ₂₀ , preferably C ₁₂ -C ₁₈ -, or sulfuric acid monoesters of secondary, straight-chain or branched C _1Q -C _{2o alcohols} in the form of the water-soluble salts or
• b) sulfated reaction products of the primary and secondary alcohols according to a) with ethylene oxide, or sulfated fatty acid alkanolamides or sulfated fatty acid monoglycerides in the form of the water-soluble salts, or composed of mixtures of a) and b).

The proportions of the stabilizer system consisting of the suspension stabilizer and the stabilizing aid in the suspension according to the invention are preferably in the range from 0.5 to 5% by weight. Amounts of 1 to 3% by weight and in particular those of 1.5 to 2.5% by weight, based in each case on the stabilized aqueous zeolite suspension, are particularly preferred. Within these quantitative ranges, the ratio of the nonionic surfactant to the anionic sulfate surfactant is in the range from 5: 1 to 1: 5, and preferably in the range from 3: 1 to 1: 1.

The suspension according to the invention is low-viscosity over the entire temperature range from room temperature to 80 ° C. and can be stirred and pumped without problems. Room temperature is understood here to mean the temperatures in the storage and processing rooms, which fluctuate between 15 and 25 ° C, depending on the season. Even after storage for several days in this temperature range, in particular at elevated temperatures of 50 to 70 ° C., only a slight, soft sediment is formed which can be easily stirred up again. In addition to the good stability properties, the suspension according to the invention also shows excellent rheological properties, which are characterized above all by a narrow viscosity range and by perfect flow behavior. In some technical processing equipment for zeolite suspensions for the production of powder detergents, the zeolite suspension must be warmed up, i.e. H. above room temperature. It is then crucial for usability that the suspension remains stable over a longer period of time at elevated temperature and does not disintegrate. In addition, the pH value of the aqueous zeolite suspension, which is at pH 11 to 14, is not significantly changed by the stabilizer system according to the invention consisting of nonionic surfactant and anionic sulfate surfactant. The pH fluctuations caused by the free alkali present in industrial production have a significantly reduced influence on the stability of the suspension when the stabilizer system according to the invention is used.

In addition, it has been found that the viscosities of these suspensions at low temperatures, i.e. H. below 50 ° C, can be further reduced, thus improving the technical applicability of the suspensions. The reduction in viscosity by lowering the zeolite concentration was eliminated as a technical measure; because, for economic reasons, high concentrations of zeolite in the suspension were to be aimed for.

The further reduction in viscosity is achieved by a targeted lowering of the pH by adjusting the suspensions to a pH of less than 12, in particular from 9 to 11, and adjusting this pH by adding an acidic salt. The addition of acidic salt is generally in the range from 0.2 to 3% by weight, based on the finished suspension in which this salt is then present as a neutral salt.

The stabilizer system according to the invention has no negative influence on the calcium binding capacity of the zeolite. The stabilizer system according to the invention consists of a mixture of detergent substances known per se; The zeolite suspension stabilized with it is therefore not only useful for the production of a large number of detergents and cleaning agents, but these detergent active substances reaching the finished detergents and cleaning agents via the zeolite suspension make a contribution to the washing and cleaning success of the finished product . The neutral salts formed from the acidic salts are also generally used as components of detergents and cleaning agents.

Aqueous zeolite suspensions with an addition of dispersants from the group of the water-soluble nonionic surfactants and the synthetic organic surfactants of the sulfonate type are known from US Pat. No. 3,254,034 (Dwyer et al). These known zeolite suspensions are used to exchange the sodium cations for the cations of the rare earths and then to process the exchanged zeolites into catalysts. In these known suspensions, which are constantly moved, special storage stability is not important; It is important, however, that only readily soluble compounds which can be easily separated off again after the cation exchange by filtration can be considered as organic additives. Thus, the person skilled in the production and improvement of stabilized zeolite suspensions for further processing into detergents was unable to draw any suggestions from the teaching of the aforementioned US patent Dwyer et al because of the different problems. In fact, the dispersants in the Dwyer et al reference, in particular the alkylbenzenesulfonic acids and ligninsulfonic acids recommended there, have proven unsuitable for the purposes of the present invention. Other synthetic sulfonate surfactants that are generally used in detergents, such as. As dodecylbenzenesulfonic acid, have no stabilizing effect on the zeolite suspensions stabilized with poorly soluble nonionic surfactants. Even from the neighboring technical field of liquid abrasives, where there are numerous proposals for the homogenization and stabilization of the suspensions of finely divided abrasives, the person skilled in the art was unable to use any for the stabilization of zeolite suspensions Derive knowledge. Rather, it has been shown that the problems to be solved in the stabilization of aqueous pigment suspensions are not of a general nature, but rather arise in a specific manner with the various pigment compounds. The stabilization of specific pigment suspensions, e.g. B. Titanium dioxide or quartz powder, results achieved can therefore not be applied to the problem solution with zeolite suspensions. In the stabilized zeolite suspensions according to the present invention, the nonionic surfactant defined above is generally in amounts of 0.2 to 3% by weight and the stabilizing aid in accordance with a) and / or b) as defined above in amounts of 0.2 to 3 wt .-% present, the total amount of nonionic surfactant and stabilizing aid in the range 0.5 to 5 wt .-%, based on the stabilized zeolite suspension. In general, however, in order to achieve the improved viscosity and storage properties, it is not necessary to add the maximum amounts mentioned; rather, total quantities of up to 2.5% by weight are sufficient for most further processing purposes.

The pH of aqueous zeolite suspensions which do not contain a stabilizer or a stabilizer which does not influence the pH is from pH 11 to pH 14, i.e. H. there is an excess of alkali. This alkali excess is often welcomed for further processing into detergents and cleaning agents because it enters the final detergent product as an alkali reserve. If the pH value is lowered by the further addition of the acid salt, the corresponding neutral salts are formed which, when the acid salts are selected appropriately, are also considered to be typical detergent and cleaning agent constituents because they impart advantageous properties to the finished product.

The partial neutralization of freshly prepared alkaline zeolite suspensions is already known as a measure to achieve a specific purpose. For example, the German Offenlegungsschrift 25 14 399 proposes adding acid to the suspension of a large-scale zeolite to lower the pH to 8.5 to 11 before the subsequent drying to a zeolite powder, in order to avoid excessive agglomeration of the zeolite -Avoid particles during drying and the formation of oversize (grit). In German Offenlegungsschrift 27 04 310, a production method for zeolite NaA is described, in which prior to increasing the volume / time _- yield operates with an increased alkali content and the alkali excess after the crystallization step by washing with water or the addition of free acid removed . Finally, German Offenlegungsschrift 26 52 409 recommends adding acid or an acid salt to the freshly prepared zeolite suspension to such an extent that the pH does not drop below 9.0. This measure improves the buffering capacity of the zeolite. The references mentioned also explain that special precautions must be taken when admixing the acid so that there is no local over-concentration of acid and the acid-sensitive zeolite structure is not destroyed.

After the acidic salt has been added to the stabilized zeolite suspension, the neutral salt formed from the acidic salt is present in the suspension in the dissolved state. German Offenlegungsschrift 26 15 698 describes the addition of a non-surfactant, organic or inorganic low molecular weight salt as a stabilization aid to a stabilized zeolite suspension, but also the European patent application EP-A-870 describes the improvement of the rheological properties of zeolite suspensions the addition of sodium sulfate neutral salt is known, but this prior art, either as a single document or together, does not suggest adding an acidic salt for targeted pH adjustment to an aqueous zeolite suspension already stabilized by a stabilizer system comprising a nonionic and a sulfate surfactant , and so to arrive at the desired narrow range of low viscosity, which is not very temperature-dependent.

The constituents of the stabilizer system of the anionic sulfate surfactants according to a) are preferably the sulfuric acid monoester of a primary C ₁₂ -C ₁₈ alkanol in the form of the water-soluble salt, and as sulfate surfactant according to b) preferably the sulfuric acid monoester of a primary C ₁₂ -C _1S - reacted with ethylene oxide Alkanol, also in the form of the water-soluble salt, used. The degree of ethoxylation of the sulfate surfactants according to b) is generally on average 1 to 15 moles of ethylene oxide per mole of the alkanol, preferably 1 to 4 moles of ethylene oxide. To produce the sulfate surfactants according to a) and b), the C ₁₂ -C _1S fatty alcohols which can be prepared from natural fats are particularly preferred. Derivatives of this type combine the particularly good stabilizing properties with those of perfect biodegradability and good accessibility from natural renewable raw materials.

Typical representatives of the sulfate surfactants used according to the invention are, for example, the products tallow alcohol sulfate (TAS) (where "tallow alcohol" stands for the hydrogenated tallow fat-alcohol mixture of the chain length range C ₁₄ -C ₁₈ ); Lauryl alcohol sulfate; Coconut alcohol sulfate (KOAS) (where "coconut alcohol" stands for the C _t2 / C _{t8 cut} from natural coconut fatty _alcohol ); Lauryl alcohol ether sulfate (LAES) (made from a C _{12 /} C ₁₄ fatty alcohol reacted with 2 to 3 moles of ethylene oxide); Coconut / tallow alcohol sulfate (made from coconut and tallow alcohol in a 1: 1 ratio); Cetyl / stearyl alcohol sulfate (Applicant's Lanette E product); Tallow alcohol 2EO sulfate. The sulfate surfactants are present as sodium salts or as ethanolamine salts or triethanolamine salts.

The practically water-insoluble nonionic surfactants used as suspension stabilizers are compounds whose cloud point, when determined according to method DIN 53917 in aqueous butyl diglycol solution, is 90 ° C. and below, preferably 85 ° C. and below . These nonionic surfactants are described in detail in German Offenlegungsschriften 25 27 388 and 26 15 698. Typical representatives for these practically water-insoluble nonionic surfactants, which are known as have proven particularly useful, e.g. B. the compounds tallow alcohol polyglycol ether with 5 moles of ethylene oxide (TA 5EO); Coconut alcohol (C ₁₂ -C _{1S cut} ) polyglycol ether with 4 moles of ethylene oxide; Oleyl alcohol polyglycol ether with 5 moles of ethylene oxide; Oleyl / cetyl alcohol polyglycol ether with 7 moles of EO (made from an alcohol mixture with an iodine number of 50 to 55); C ₁₄ -C ₁₅ oxo alcohol polyglycol ether with 4 moles of EO; Nonylphenol polyglycol ether with 5 moles of ethylene oxide.

The amount of the acid salt is generally in the range from 0.2 to 3% by weight, based on the finished suspension. In individual cases, the additional quantities can also be above or below these range limits. In any case, the amount of acid salt added depends on the pH of the moist zeolite filter cake or the zeolite suspension at the end of the zeolite production process. The pH value is therefore not only dependent on the choice of the zeolite production process, but also on the degree of washing out of the zeolite with water. The acidic salt is added in solid form or in the form of a concentrated aqueous solution in small portions with stirring.

Acid salts which can be used according to the invention are primarily inorganic acid salts, in particular the acid salts of sulfuric acid, carbonic acid, phosphoric acid and polyphosphoric acids, boric acid and silica. Usable, although less preferred, are the acidic salts of polyvalent organic acids, such as. B. citric acid, diglycolic acid, gluconic acid, polyacrylic acid, nitrilotriacetic acid, hydroxyethane diphosphonic acid and analogous hydroxyalkane or aminoalkane polyphosphonic acids. In principle, the acid salts of other inorganic and organic acids are also suitable; however, those acidic salts are preferred which are present after the partial neutralization as such neutral salts which play an advantageous role in building up the detergent and cleaning agent or during the washing or cleaning process. Acid salts are accordingly the salts of polyvalent acids which have at least one alkali or ammonium cation and react with the alkali in the aqueous zeolite suspension with partial neutralization.

The zeolite A used according to the invention can be prepared by numerous known processes by hydrothermal synthesis from sodium silicate and sodium aluminate solutions or from destructured kaolin and sodium hydroxide. A number of processes have become known for the industrial production of zeolite A for detergent purposes, in which the zeolite A crystals are formed with rounded corners and edges and the formation of oversize (grit) is avoided by specific process parameters. Such methods are described, for example, in German Offenlegungsschriften 24 47 021, 25 17 218, 25 33 614, 26 51 419, 28 51 420, 26 51 436, 26 51 437, 26 51 445, 26 51 485, 27 04 310, 27 34 296, 29 41 636, 30 11 834. 30 21 370.

In hydrothermal synthesis, zeolite A is generally obtained as a moist filter cake with about 50 to 60% water content. Because of its thixotropic properties, this filter cake can be easily stirred immediately after production and mixed directly with the suspension stabilizer.

The suspensions according to the invention can be prepared by simply mixing the components. In practice, the aqueous suspension of the zeolite, which is still moist and undried from its production, is preferably used by converting the moist filter cake obtained after separating the mother liquor and washing with water into a flowable suspension by stirring. A further addition of water is generally not necessary. The stabilizers are used in the case of nonionic surfactants in undiluted form and in the case of anionic sulfate surfactants in the form of the commercially available technical aqueous concentrates of the sodium salts or as granules, flakes or pasta. The acidic salts are usually added in powder form. The amount of water additionally introduced with paste-like concentrates is small in quantity, so that it does not significantly influence the zeolite concentration in the stabilized suspension. The suspensions according to the invention can be prepared with zeolite concentrations of at least 20% by weight; however, for economic reasons, i.e. H. at z. B. to save transport and energy costs, set the water content in the suspensions as low as possible. For example, efforts will be made to adjust the zeolite content to values above 40% by weight and, if possible, to values around 50% by weight. The suspensions according to the invention are generally prepared at elevated temperatures, ie. H. at approx. 50 ° C, which speeds up the mixing process. Of course, an already dried zeolite powder can also be used for the production of the suspensions according to the invention if the zeolite filter cake which is still moist from the production is not available.

For further processing into detergents and cleaning agents, the stabilized zeolite suspensions are used as a liquid raw material according to the usual manufacturing processes for such agents. The use of the stabilized zeolite suspensions for the production of powdered detergents by the method of hot spray drying is of particular technical importance, the so-called slurry batch being produced with the zeolite suspension and then converted into a detergent powder in the usual manner in spray towers. In special cases, for example when pulverulent preliminary and intermediate products are to be produced, the suspension according to the invention can also be converted into a spray-dried powder as such or after the addition of further detergent substances. It was found as a special property of the spray-dried suspension that the resulting powder product can be stirred up again with water to form a stable suspension, which increases the practical application possibilities for the suspension according to the invention.

Examples 1. Stabilizer system composed of nonionic surfactant and anionic sulfate surfactant

• Gehalt an Zeolith NaA, bezogen auf die wasserfreie Substanz (Glührückstand nach einstündigem Erhitzen auf 800°C): 47,0 %;
• Calciumbindevermögen: 163 mg CaO/g wasserfreier Substanz (bestimmt nach der unten angegebenen Methode);
• Teilchengrößenbestimmung (Coulter-Counter, Volumenverteilung): 100 % kleiner als 15 µ; 98,1 % kleiner als 10 µ; 79 % kleiner als 5 µ; 36,5 % kleiner als 3 µ;
• mittlerer Teilchendurchmesser: 3,9 µ;
• Alkaligehalt: 0,35 Gew.-%.

A moist filter cake of zeolite NaA with the following properties was used to prepare the stabilized suspensions:

• Zeolite NaA content, based on the anhydrous substance (residue on ignition after heating at 800 ° C. for one hour): 47.0%;
• Calcium binding capacity: 163 mg CaO / g anhydrous substance (determined according to the method given below);
• Particle size determination (Coulter counter, volume distribution): 100% smaller than 15 µ; 98.1% less than 10 µ; 79% less than 5 µ; 36.5% less than 3 µ;
• average particle diameter: 3.9 µ;
• Alkali content: 0.35% by weight.

Method for determining calcium binding capacity:

1 l of an aqueous solution containing 0.594 g of CaCl ₂ (corresponding to 300 mg of CaO / l = 30 ° d) was adjusted to a pH of 10 using dilute sodium hydroxide solution and, with stirring, 2.13 g of the filter cake (= 1, 00 g of anhydrous zeolite A) are added. The suspension was then stirred at a temperature of 22 ± 2 ° C for 10 minutes. After the zeolite had been filtered off, the residual hardness X in the filtrate was determined by complexometric titration with ethylenediaminetetraacetic acid; the calcium binding capacity in mg CaO / g is then calculated using the formula: (30 - X). 10th

General method for the preparation of the stabilized zeolite A suspensions:

In each case, batches of 1 kg of the fresh, 60 ° C. warm, moist zeolite A filter cake (approx. 53% by weight of water) were stirred up. Mixing intensity approx. 500 revolutions per minute. Under these conditions, the filter cake becomes an easily stirrable suspension. The mixture of stabilizer and stabilizing aid was introduced into this suspension. The solid or viscous additives at room temperature were first liquefied on the steam bath and then added. Mixing time approx. 2 to 3 minutes.

example 1

• 1,5 Gew.-% Talgfettalkohol, umgesetzt mit 5 Mol Ethylenoxid (TA 5 EO),
• 0,8 Gew.-% Talgfettalkoholsulfat (TAS),
• 46,0 Gew.-% Zeolith NaA,
• 0,35 Gew.-% Natriumoxid,
• Rest Wasser.

In this example, the dependence of the viscosity of the stabilized zeolite A suspension on the temperature is given. The stabilized suspension had the following composition:

• 1.5% by weight of tallow fatty alcohol, reacted with 5 moles of ethylene oxide (TA 5 EO),
• 0.8% by weight of tallow fatty alcohol sulfate (TAS),
• 46.0% by weight of zeolite NaA,
• 0.35% by weight sodium oxide,
• Rest of water.

A comparison was made with a stabilized suspension of the prior art which contained only 1.5% by weight of TA 5 EO.

The Brookfield viscosity was determined: 20 revolutions per minute; Spindle depending on the viscosity range.

When the viscosity values are compared, the viscosity behavior of the suspension according to the invention extends practically over the entire temperature range.

Examples 2 to 4

These examples describe bench tests of three suspensions according to the invention in comparison to a known suspension (see Example 1). The stored suspensions are based on the criteria of sedimentation, i.e. H. Sediment formation, and sediment consistency assessed.

Test method

250 ml screw-top jars were used as containers for the storage test. The filling level of the freshly filled suspension was set to 100%. After the storage period, the height of the clear liquid zone above the suspension was measured and the sedimentation behavior was expressed in "% suspension". Accordingly, "100% suspension" means that no clear liquid phase has formed.

• B_F ≠ kein Bodensatz in der Suspension;
• B_w+ = geringe Bodensatzbildung, weich, leicht aufrührbar;
• B_w = Bodensatzbildung mit weicher Konsistenz, leicht aufrührbar;
• B_M - Bodensatzbildung mit mittlerer Konsistenz, schwer aufrührbar;
• B_H - Bodensatzbildung mit harter Konsistenz, nicht aufrührbar.

The consistency of the sediment that had formed after storage was also checked in the same vessels by scanning with a glass rod. When assessing the sediment, it is not only important whether and to what extent a sediment has formed, but also whether this sediment is easy or difficult to stir or not at all. The following grades were therefore chosen:

• B _F ≠ no sediment in the suspension;
• B _w + = low sediment formation, soft, easy to stir;
• B _w = sediment formation with a soft consistency, easy to stir;
• B _M - sediment formation with medium consistency, difficult to stir;
• B _H - sediment formation with a hard consistency, cannot be stirred.

The storage tests were carried out at room temperature, 35 ° C, 50 ° C and 70 ° C. The viscosity of the suspensions was also measured at these temperatures before storage; no change in viscosity was observed during the storage period in the case of the completely homogeneous suspensions and in the case of the again stirred suspensions with a soft sediment consistency.

In Examples 2 to 4, the abbreviations TA 5 EO and TAS have the meanings given in Example 1. KOAS means coconut oil alcohol sulfate sodium salt (C ₁₄ -C _{18 cut} ). LAES means lauryl alcohol (C ₁₂ / C ₁₄ ) ether sulfate sodium salt (with approx. 2 mol EO).

These storage tests show (see table below) that the suspensions according to the invention are stable even at elevated temperature and can be processed without problems after storage. This improved stability at elevated temperature is particularly advantageous when the further processing method requires the suspension to be used at elevated temperature or to be heated to elevated temperature.

If one uses mixtures of zeolite NaA and hydrosodalite, e.g. B. in a ratio of 10: 1 to 1: 1, or mixtures of zeolite NaA and zeolite NaX, then comparable stability properties are observed.

11. Stabilizer system consisting of nonionic surfactant and anionic sulfate surfactant and with the addition of an acidic salt

• Gehalt an Zeolith A: 46 %;
• Calciumbindevermögen: 160 mg CaO/g;
• Teilchengröße: 100 % kleiner als 25 µ; 95 % kleiner als 10 µ;
• 71 % kleiner als 5 µ; 18 % kleiner als 3 µ;
• mittlerer Teilchendurchmesser: 4,0 µ;
• Alkaligehalt: 0,35 Gew.-%.

The zeolite A filter cake used had the following properties:

• Zeolite A content: 46%;
• Calcium binding capacity: 160 mg CaO / g;
• Particle size: 100% smaller than 25 µ; 95% less than 10 µ;
• 71% less than 5 µ; 18% less than 3 µ;
• average particle diameter: 4.0 µ;
• Alkali content: 0.35% by weight.

To prepare the stabilized zeolite A suspensions, batches of 1 kg of the fresh, 60 ° C. warm, moist zeolite A filter cake (approx. 54% by weight of water) were stirred. Mixing intensity approx. 500 revolutions per minute. Under these conditions, the filter cake becomes an easily stirrable suspension. The acid salt and then the mixture of stabilizer and stabilizer were first introduced into this suspension. The solid or viscous additives at room temperature were first liquefied on the steam bath and then added. Mixing time approx. 2 to 3 minutes. The acid salt was mixed in in solid, finely divided form.

Example 5

In this example, the dependence of the viscosity of the stabilized zeolite A suspension on the temperature is given. The stabilized suspension had the following composition:

A comparison was made with a stabilized suspension of the prior art which contained only 1.5% by weight of TA 5 EO; pH: 13.5.

The Brookfield viscosity was determined: 20 revolutions per minute; Spindle depending on the viscosity range.

Examples 6 and 7

These examples describe standing tests of a suspension according to the invention in comparison to a known suspension. The stored suspensions are based on the criteria of sedimentation, i.e. H. Sediment formation, and sediment consistency assessed. For test method see Examples 2 to 4. The viscosity of the suspensions was measured before storage; no change in viscosity was observed during the storage period in the case of the completely homogeneous suspensions and in the case of the again stirred suspensions with a soft sediment consistency. The storage tests (see table below) show a low viscosity for the suspension according to the invention at room temperature and a slight change in viscosity when the temperature is increased to 70.degree. The suspension according to the invention is stable both at room temperature and at elevated temperature and can be processed without problems after storage.

If one uses mixtures of zeolite NaA and hydrosodalite, e.g. B. in a ratio of 10: 1 to 1: 1, or mixtures of zeolite NaA and zeolite NaX, then comparable viscosity and stability properties are observed. If the acid salt NaHS0 _{4 is} replaced by NaH ₂ P0 ₄ in Example 6, or the stabilizer TA 5 is reacted with an equal quantity mixture of oleyl / cetyl alcohol with an iodine number of 50 to 55, reacted with 4 mol or 6 mol ethylene oxide in a ratio of 1: 1, replaced, then similar viscosity and stability properties are also observed.

Claims (11)

1. A stabilized, aqueous zeolite suspension consisting of industrially produced zeolite A, water and a stabilizer system consisting of a substantially water-insoluble nonionic surfactant as suspension stabilizer and a stabilizing auxiliary, characterized in that the stabilizing auxiliary consists of an anionic sulfate surfactant selected from the group comprising

a) sulfuric acid monoesters of primary, straight-chain or branched-chain C₁₀-C₂₀, preferably C₁₂-C_l8, alcohols or sulfuric acid monoesters of secondary straight-chain or branched-chain C₁₀-C₂₀ alcohols in the form of the water-soluble salts or

b) sulfated reaction products of the primary and secondary alcohols according to a) with ethylene oxide or sulfated fatty acid alkanolamides or sulfated fatty acid monoglycerides in the form of the water-soluble salts

or of mixtures of a) and b).

2. A suspension as claimed in Claim 1, characterized in that it contains the stabilizer system in quantities of from 0.5 to 5 % by weight, preferably in quantities of from 1 to 3 % by weight and, more particularly, in quantities of from 1.5 to 2.5 % by weight.

3. A suspension as claimed in Claim 1 or 2, characterized in that the ratio of the nonionic surfactant as suspension stabilizer to the anionic sulfate surfactant as stabilizing auxiliary is in the range from 5 : 1 to 1 : 5 and preferably in the range from 3 : 1 to 1 : 1.

4. A suspension as claimed in any of Claims 1 to 3, characterized in that the nonionic surfactant is present in quantities of from 0.2 to 3 % by weight and the stabilizing auxiliary according to a) and/or b) in quantities of from 0.2 to 3 % by weight for a total quantity of from 0.5 to 5 % by weight.

5. A suspension as claimed in any of Claims 1 to 4, characterized in that the suspension has a pH-value below 12, more particularly in the range from 9 to 11, which is adjusted by addition of an acidic salt.

6. A suspension as claimed in any of Claims 1 to 5, characterized in that the acidic salt is added in a quantity of from 0.2 to 3 % by weight, based on the suspension as a whole.

7. A suspension as claimed in any of Claims 1 to 6, characterized in that it contains as anionic sulfate surfactant according to a) the sulfuric acid monoester of a primary C₁₂-C₁₈ alkanol in the form of the water-soluble salt or, according to b), the sulfuric acid monoester of a primary C₁₂-C₁₈ alkanol reacted in particular with 1 to 4 moles of ethylene oxide, again in the form of a water-soluble salt.

8. A suspension as claimed in any of Claims 1 to 7, characterized in that it contains as the anionic sulfate surfactant according to a) the sulfuric acid monoester of a C₁₂-C_I8 fatty alcohol in the form of the sodium salt or, according to b), the sulfuric acid semiester of the C₁₂-C_l8 fatty alcohol reacted in particular with 1 to 4 moles of ethylene oxide, again in the form of the sodium salt.

9. A suspension as claimed in any of Claims 1 to 8, characterized in that the acidic salt is, in particular, an acidic salt of sulfuric acid, carbonic acid, phosphoric acid, polyphosphoric acids, boric acid and silicic acid.

10. A process for preparing the suspensions claimed in any of Claims 1 to 9, characterized in that the zeolite filter cake still moist from its production is stirred and the stabilizer is added in undiluted form or as an aqueous concentrate.

11. The use of the suspensions claimed in any of Claims 1 to 9 for the production of powder-form detergents and cleaning preparations by methods known per se, more especially by the hot spray-drying of a liquid mixture prepared with the suspension.